The National Interagency Fire Center in Boise upped the national wildfire preparedness level Tuesday to the highest level for the first time in five years.

The center lists two central Idaho wildfires as the country's top priorities, helping provide crews and resources for the Beaver Creek fire, which forced the evacuation of 1,250 homes in the resort area of Ketchum and Sun Valley and has cost nearly $12 million so far.

President Barack Obama was briefed Tuesday morning on the wildfires by his homeland security adviser, Lisa Monaco. The White House said the administration's focus is on supporting state and local first responders and that Obama's team is in ongoing contact with federal and local partners.

More than 40 uncontained, active and large wildfires dot the U.S. map from Arizona to Washington state and Alaska, the White House said. About 17,800 people have been dispatched to the fires.

Steve Gage, assistant director of operations for the fire center, said they can't fill all the requests for crews and equipment from the 48 fires that remain uncontained around the country.

Gage said as fire season progresses, the center moves crews around to where the greatest assets like houses are threatened, and tries to have crews positioned to catch new fires when they are small.

In Oregon, winds that draw windsurfers to the Columbia Gorge have doubled the size of a wildfire to 10 square miles. The Government Flat fire burned two homes and threatens 150 more on the northern flanks of Mount Hood. Four days into the battle the cost has topped $1 million, said Oregon Department of Forestry spokesman Dave Morman. About 50 homes have evacuated in the area of canyons 10 miles southwest of The Dalles.

"That's one of the challenges when the fire gets into these long canyons, it's very, very difficult for firefighters," he said.

The boost in priority for Idaho's Beaver Creek fire gave fire managers resources they needed to start attacking the fire more directly, said fire spokesman Rudy Evenson. Weather conditions were also improving. The fire was 9 percent contained after burning 160 square miles and had 1,750 personnel. The cost through Monday was $11.6 million.

Nationally, federal agencies have spent more than $1 billion so far this year, about half last year's total of $1.9 billion, according to the fire center. There have been 33,000 fires that have burned 3.4 million acres.

Whether costs top the 10-year average of $1.4 billion or the $1.9 billion spent in 2012 and 2006 will depend on the rest of the wildfire season, which traditionally gets very active in Southern California as late as October, said Gage.

Professor Norman Christensen of Duke University's Nicholas School of the Environment, an expert in the environmental impacts of forest fires, said fires have been particularly intense in Colorado, California and Idaho this year.

"Certainly drought in some areas has contributed to the number and intensity of fire events," he said in an email. "But many of the fires have been in highly populated, wilderness-urban interface areas such as Colorado Springs, Sun Valley, Idaho, and the west slope of the Sierra Nevada. That adds greatly to costs since so many more resources are required to protect built structures."

Jason Sibold, assistant professor of biogeography at Colorado State University, said since the 1990s, the climate has been changing, producing hotter, drier and longer summers in the West. That combined with more people building vacation homes in the woods pushes up costs.

"The societal demand to try to control and fight these fires is escalating at the same pace as the climate's warming," he said.

Despite firefighting efforts, 963 homes and 30 commercial buildings have burned this year, according to the fire center. And 30 firefighters have died in the effort, including 19 hotshots at Yarnell, Ariz. The annual average is 17 dead over the past 10 years.

The high monetary costs come despite a 5 percent cut in firefighting budgets due to the federal spending cuts known as sequestration, which eliminated 500 firefighters and 50 wildland fire engines this year. Meanwhile, the U.S. Forest Service has yet to activate a new generation of air tankers provided by private contractors, intended to deliver bigger payloads faster.

In Montana, Gov. Steve Bullock declared a state of emergency for 31 counties, allowing the use of National Guard resources.

Wind gusts pushed two lightning-caused fires to a combined 5,000 acres, or nearly 8 square miles near Lolo in southwestern Montana. The fires burned several structures and caused residents to flee.

The rapidly spreading fires west of Lolo are a game changer that promises to stretch resources thin, Bullock told the Missoulian newspaper.